Given two textboxs (textbox1 and textbox2), you can add it content to datagridview:

Code:
dt.Rows.Add(textbox1.Text, textbox2.Text);
Obviously you had to have the two columns added in the datagridview control. Then to save it to database (I'll omit connections and queries):

Code:
SqlCommand command = new SqlCommand();
if (dt.Rows.Count > 0)
{
   for (int i = 0; i < dt.Rows.Count; i++)
...